The method of simulating the wear performance under working conditions using a high-temperature ultra-high-speed wear testing machine was adopted to study the effect of feed rate variation on the wear behavior and scraping performance of the AlSi/hBN sealing coating and TC4 simulated blades. The macro and micro morphology of the coating and blades were analyzed by stereomicroscope and scanning electron microscope (SEM). The phase composition of the coating was analyzed by energy dispersive spectrometer (EDS) and X-ray diffraction. The results showed that, under the conditions of temperature of 450°C, line velocity of 300m/s, and feed depth of 500μm, the change in feed rate significantly affected the macro and micro morphology and wear mechanism of the AlSi/hBN sealing coating-TC4 simulated blades. At low feed rates, severe wear occurred, mainly manifested as grooving, adhesion transfer, and overheating mechanisms. At medium to high feed rates, good machinability was observed, mainly manifested as cutting and transfer of coating material to the blades.

Thermally sprayed abradable coatings are essential for improving the performance of gas turbine engines. They act as a protective barrier between the stationary casing and rotating blades. Though a lot of research has been done on abradable coatings, little attention has been paid to comprehending wear mechanisms in the abradable-blade tip interaction. The goal of this project is to create a cost-effective test rig that can evaluate different thermally sprayed abradable coatings and understand how they interact with titanium blade tips under application-relevant conditions. Blade tip velocity, incursion rates, incursion depths, reaction forces, and interfacial temperatures are some of the inputs and outputs that the testing rig can provide. Aiming to validate the rig, this study examined the wear behavior of aluminum, thermally sprayed polyester, and AlSi-40Polyester abradable coating. The reaction forces for aluminum and polyester were overall higher when compared to AlSi-40Polyester. However, thermally sprayed polyester showed the highest interfacial temperatures of all materials tested. The difference in the reaction forces and interfacial temperature correlates well with the different wear mechanisms and thermal conductivities. Overall, the equipment showed to be a promising pre-screening methodology to evaluate and develop novel thermal spray abradable coatings.

Compressor abradables coming into operational contact with bare, un-tipped titanium alloy rotor blades over a wide range of incursion conditions require excellent cuttability in order to avoid blade tip damage by wear and over-heating. This is more easily achieved for low temperature systems that can make use of low shear strength aluminum matrices than for compressor abradables operating closer to the maximum allowable temperature of advanced titanium alloy blade materials. In this case the rotor path linings will have to incorporate higher temperature resistant Ni and Co alloy matrices. To that end the availability of abradable coatings capable of operating at up to 550°C while showing little thermal ageing effects and excellent abradability over their entire service life can influence the compressor blade material selection and therefore compressor weight and performance characteristics. This paper provides an overview of titanium blade friendly compressor abradable concepts. Particular emphasis will be placed on the abradability of in-service and next-generation coatings designed for use up to the temperature capability of Ti blade rotor materials and beyond. Candidate coatings are also screened for other performance criteria such as thermal cyclic resistance and ageing behaviour.